Endoscopic instruments with a flexible shank, with which an actively controllable section of the shank consists of several segments manufactured from tube sections, are already known. These segments are connected to one another in a pivotally movable manner by way of joints. Tension or pull means which are led in the inside of the segments, serve for the control of the pivot movement. For the pivot movement, it is necessary for an adequately large gap to be present between two adjacent segments, so that the pivoting movement is not limited to small angles due to mutual contacting of the segments. The actively controllable section of the shank is coated with a flexible tube which seals the components installed in the instrument, to the outside, and represents a barrier to the surroundings.
Thereby, a common problem is thereby the fact that folds or creases occur in the flexible tube, and these are caused over the course of time when using the endoscopic instrument. Thus inwardly arched folds can occur between two adjacent segments in the region of the gaps. The flexible tube can thereby become clamped between the segments. This can lead to a restriction of the pivot movability of the flexible shank as well as to a perforation of the flexible tube. Approaches for solving this problem lie in the provision of additional fine meshwork between the flexible section and the flexible tube, as well as the use of a thick-walled flexible tube which is less prone to the formation of creases or folds. Likewise, it is known to apply many short segments, so that the complete angled bending of the endoscopic instrument is achieved by only small pivot movements of the segments, and the gaps between two adjacent segments can therefore be kept small. The disadvantage of such solution is the fact that an additional meshwork as well as a thick-walled flexible tube leads to an increased outer diameter of the endoscopic instrument, whereas short segments increase the assembly effort and enlarge the bending radius.